Unitized window wall systems have been used for skyscrapers and building structural systems. The unitized window wall system provides window panels that come with mullion frames within the panel before being installed to the building façade. The window panels include a glazing, which comes with double or triple glass panes (double glass panes with a thin film between) and is filled with a noble gas. The noble gas, typically argon or xenon, is used for thermal insulation and is installed on an exterior side of the mullion frames. The mullion frames then attach to one another by a series of clips or are fastened with bolts and nuts to the building structural system.
However, the unitized window wall system has limited space, which causes low thermal resistance and does not allow for additional layers of glazing panel. Further, the unitized window wall system is difficult to maintain and clean due to exposed mullion systems. Moreover, the unitized window wall system requires complex installation, typically off-site, leading to additional costs.
Thus, there is a need for a window or curtain wall assembly which addresses the above problems.